Date of Award

Fall 1995

Document Type

Thesis - Restricted

Degree Name

Master of Science (MS)

Department

Electrical and Computer Engineering

Abstract

Optical current sensors employing the Faraday effect have been investigated to provide an accurate and isolated measurement of current. However, such optical current sensors are only used in limited applications. This is because the implementation requires precision optical components, light sources, detectors, and a complex electronic circuit. This, in turn, results in a high cost device. Alternative current sensing methods include current transformers, thermal devices, shunt current sensing, hall effect devices, and magneto resistive elements. Some of these methods are relatively low cost due to their simple configurations. However, a simple, low cost optical current sensor can be designed capable of performing as well as other sensors based on other technologies. This thesis will examine four simple optical configurations which have potential to result in practical, low cost, optical current sensing devices. Each configuration utilizes plastic optical fibers, film polarizers, and a high Verdet constant glass known as SF57 as the sensing element. These components are inexpensive and the resulting configurations are capable of tolerating small mechanical variations. The sensors have reduced sensitivity compared to previously designed sensors based on the Faraday effect. However, the sensitivity is more than adequate for high power applications where the isolation of the measurement is an advantage. Design equations which relate fiber diameter and sensing glass length to sensitivity are given and design trade-offs are discussed.

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